Method for producing sealing elements

ABSTRACT

A method for producing annular metallic sealing elements by bringing at least two sheet metal strips or foil strips having predefinable thicknesses, lengths, and widths into operative connection with each other in the manner of a tailored blank or patchwork, subsequently winding this composite to obtain a tube, wherein the mutually facing end regions of the tubular multilayer composite are connected to each other non-positively or positively or by bonding, or combinations thereof, notably by thermal action such as by welding or soldering, and either dividing the tube into individual ring elements, which are subsequently formed using mechanical shape-forming to obtain the respective sealing element, or forming the entire tube and dividing the tube thus profiled into ring elements to obtain individual sealing elements.

BACKGROUND OF THE INVENTION

The invention relates to a method for producing annular metallic sealing elements.

A sealing element has been disclosed by EP 1 306 589 A2, containing a first metallic layer comprising an oxide dispersion-strengthened alloy and a second metallic layer comprising a solid solution-hardened alloy, or a precipitation-hardened nickel-based alloy, or an oxide dispersion-strengthened alloy. As seen in a radial sectional view, the seal has a bellows-like structure. From a process engineering point of view, first and second pieces of the layers are cut out, with the two layers being formed to obtain first and second rings. The rings thus obtained are placed inside each other concentrically, and the material composite thus obtained is subsequently shaped to produce the end contour of a sealing element. Given the multiple work steps, this kind of shape-forming is considered to be complex and costly.

DE 10 2007 038 713 A1 discloses a method for producing regionally reinforced hollow profiled sections from a metal, in particular steel or a steel alloy. A blank, together with a plurality of metal reinforcement elements disposed on the blank, are formed so as to obtain a hollow profiled section, by employing a roll-forming technique or by way of U-O forming, wherein the reinforcement elements disposed on the blank are positively connected to the formed blanks following the forming operation.

Today, metallic sealing elements are often die-cut from sheet metals so as to obtain these elements and are brought into the final shapes thereof in a multiple work steps. The use of sheet metals results in much loss of material during die-cutting of the base sealing body, and thus the material costs are very high.

SUMMARY OF THE INVENTION

It is the object of the invention to produce sealing elements that can improve both the sealing properties and the resilience properties in the operational stage, using the lowest possible amount of material.

The sealing elements thus produced should be suitable for specific applications, notably in the area of vehicle drive systems.

This object is achieved by a method for producing annular metallic sealing elements by bringing at least two sheet metal strips or foil strips having predefinable thicknesses, lengths, and widths into operative connection with each other in the manner of a tailored blank or patchwork, and subsequently winding this composite to obtain a tube, wherein the mutually facing end regions of the tubular multilayer composite are connected to each other non-positively or positively or by bonding, or combinations thereof, notably by thermal action such as by welding or soldering, and either dividing the tube into individual ring elements, which are subsequently formed using mechanical shape-forming to obtain the respective sealing element, or forming the entire tube and dividing the tube thus profiled into ring elements to obtain individual sealing elements.

This object is likewise achieved by a method for producing annular metallic sealing elements by generating tubes or tube segments having various external dimensions from sheet metal strips or foil strips having predefinable thicknesses, lengths, and widths, placing the tubes or tube segments inside each other to obtain a multilayer composite designed in the manner of tailored tubes, wherein the mutually facing end regions of the tubular multilayer composite are connected to each other non-positively or positively or by bonding, or combinations thereof, notably by thermal action such as by welding or soldering, and either dividing the multilayer composite into individual ring elements, which are subsequently formed using mechanical shape-forming to obtain the respective sealing element, or forming the entire tube and dividing the tube thus profiled into ring elements to obtain individual sealing elements.

The term ‘tailored blank’ is considered by a person skilled in the art to mean sheet metals or foils that are composed, for example, of various material grades and/or thicknesses. This prefabricated semi-finished product subsequently undergoes a mechanical forming operation.

The term ‘patchwork’ is considered by a person skilled in the art to mean sheet metals or foils that are placed onto other smaller sheet metals or foils in the manner of patches and connected to the first sheet metals or foils.

The term ‘tailored tubes’ is considered by a person skilled in the art to mean tubular components that are formed by sheet metals or foils and are connected to each other.

The connection of the sheet metals, or the tubes, or the mutually opposing end regions of the wound sheet metals can be effected by all bonding, non-positive or positive connecting methods known in the art, or combinations thereof.

Fields of application for sealing elements produced by a method according to the invention include gaskets in the area of a turbocharger, or flat gaskets or flange gaskets, notably in the exhaust tract of a motor vehicle. Moreover, the gaskets thus generated can be employed as housing seals, for example in the transmission housing of a vehicle.

Possible starting materials are either thin sheet metal strips or foil strips (10 μm to 200 μm), or combinations with thicker sheet metal strips or foil strips (200 μm to 1,000 μm), of which the respective material composite is composed, either in the form of a sheet metal or a tube.

Given the various lengths, widths or thicknesses of the sheet metal strips or foil strips employed a leaf spring-like layered structure (patchwork) can, for example, be implemented. This is associated with the following advantages:

-   -   This layer structure is used to be able to adjust resilience         properties similar to those of a leaf spring, in keeping with         the requirements for the sealing element.     -   Given the layer structure, combinations comprising thinner and         thicker sheet metals/foils can be generated, so that thinner,         and thus less rigid, rings are attached to the inside or outside         of the sealing element, which lay in closer contact with the         sealing surfaces and thus achieve the sealing function, while         one or more thicker sheet metals in the center of this         multilayer composite introduce the necessary rigidity into the         system, so as to ensure the required resilience function.

Such layer systems can be produced from materials that do not result in any undesirable effects, such as varying thermal expansions or thermoelectric effects, for example.

Depending on the field of use of the sealing element, identical or different materials are employed. Suitable materials include cold rolled strips, spring steels, nickel-based alloys, bainitic materials, or the like.

The sheet metal strips or foil strips employed can be coated as needed in some regions or over the entire surface.

The subject matter of the invention is shown in the drawings based on an exemplary embodiment and is described as follows. In the drawings:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a layer composite that is composed in the manner of a tailored blank;

FIG. 2 is a schematic diagram of a layer composite that is composed in the manner of a patchwork;

FIGS. 3 and 4 are schematic diagrams of two tubes that are rolled from sheet metals having different rolling directions;

FIG. 5 is a schematic diagram of a tube wound helically from a long sheet metal strip;

FIGS. 6 and 7 are schematic diagrams of shape-forming operations for contouring a tube;

FIG. 8 is a schematic diagram of a shape-forming operation for generating a sealing element;

FIG. 9 is a schematic diagram of sealing elements having various designs; and

FIG. 10 is a schematic diagram of a cylinder-head gasket, containing a sealing element according to FIG. 9.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a schematic diagram of a layer composite that is composed in the manner of a tailored blank and formed by three sheet metal strips 1, 2, 3 having various thicknesses. In this example, the respective lengths L and widths B of the sheet metal strips 1, 2, 3 are the same. The thicknesses of the sheet metal strips 1 and 3 range between 200 and 1,000 μm, while the thickness of the interposed sheet metal strip 2 ranges between 10 and 150 μm. This thickness information shall only be regarded as thickness information that is provided by way of example. In the region of one of the sides 4, the sheet metal strips 1, 2, 3 can be connected to each other by thermal action, for example by welding (not shown). A multilayer composite is thus generated, which is formed by the sheet metal strips 1, 2, 3 and is subsequently wound to obtain a tube 5. The mutually opposing end regions 6, 7 of the wound tube 5 can likewise be connected to each other by thermal action, for example by welding. This will depend on the particular use of the sealing element to be generated. If a joint—as is known for piston rings—should be required, the tube 5 can be designed in the appropriate manner as a tube segment, so that this joint (not shown) is maintained after the winding operation.

FIG. 2 shows an alternative to FIG. 1. Here, a plurality of sheet metals 8, 9, 10 having substantially different thicknesses have been arranged adjoining each other. In this example, these sheet metals 8 to 10 are connected to each other by bonding (adhesion, welding, soldering). The patchwork thus generated is rolled (arrow), wherein the end regions are connected to each other analogously to FIG. 1. In this way, a tube 5′ is obtained, having various thicknesses, as seen looking in the radial direction, or thickened regions in predefinable locations. This tube 5′ can subsequently be cut into individual ring elements, or the entire tube 5′ can be formed. Individual ring elements used to obtain sealing rings can be cut from the formed tube 5′.

FIGS. 3 and 4 show sheet metal strips 11, 12 that have different rolling directions and are likewise formed so as to obtain tubes 13, 14. As previously addressed, the respective end regions 15, 16, 17, 18 of the tubes 13, 14 can be connected to each other by welding or soldering. Here as well, tube segments can be formed, so that the end regions 15, 16, 17, 18 are provided at a predefinable distance from each other. In this example, the tubes 13, 14 have different diameters, with the outside diameter of the tube 14 approximately corresponding to the inside diameter of the tube 13. These tubes 13, 14 can now be pushed inside each other so as to generate a tailored tube. Any weld seams that may be present can be provided offset from each other, as needed. It is likewise conceivable to position the tubes 13, 14 relative to each other so that they are brought into operative connection with each other by welding.

FIG. 5 shows another embodiment of the method according to the invention. A long sheet metal strip 19 can be wound to obtain a helical tube 20. The end region 21 of the sheet metal strip 19 can be connected to the winding region 22 by welding or soldering, if necessary. It is also conceivable to generate a positive or non-positive connection so as to connect the individual layers to each other.

The tubes, or tube segments, generated in accordance with FIGS. 1 to 5 are now separated (for example by cutting) so as to obtain the corresponding ring elements, and supplied to a further processing operation. As addressed above, it is also possible to form the entire tube, wherein the tube thus profiled is cut into ring elements so as to obtain individual sealing elements.

Suitable methods for this purpose include forming methods, such as hydroforming, rubber pad forming, or the use of upsetting presses. A person skilled in the art will select a suitable method, depending on the application.

FIGS. 6 and 7 show various shape-forming processes for contouring the outer circumferential surface, for example of the tube 20 according to FIG. 5. FIG. 6 shows the process of hydroforming, and FIG. 7 shows the process of rubber pad forming. In both instances, appropriate contours 20′, 20″ are introduced into the tube 20.

FIG. 8 shows an enlarged view of an individual ring element 23. This ring element 23 is placed in front of a negative mold 24, which is provided with a corresponding negative profile 25. Using a rotating roller 26, for example, the ring element 23 is pressed into the negative mold 25. Following the mechanical shape-forming operation, the sealing element 27 thus generated has a substantially V-shaped contour. Depending on the design of the negative mold 25, a wide variety of contours of the sealing element 27 can be generated.

FIG. 9 shows examples of sealing elements 27 having various contours.

FIG. 10 is a schematic diagram of a flat gasket or a cylinder-head gasket 28, such as can be used, for example, in the area of an internal combustion engine. Screw through-holes 29 and through-holes or combustion chamber through-passages 30 are apparent. A sealing element 27, such as is shown in FIG. 9, can be positioned in the region of the respective through-holes or combustion chamber through-passage 30. 

1. A method for producing annular metallic sealing elements, comprising bringing at least two sheet metal strips or foil strips having predetermined thicknesses, lengths, and widths into operative connection with each other to form a multiplayer composite, winding the composite to obtain a tube, operatively connecting mutually opposed end regions of the tubular multilayer composite to each other, and dividing the tube into individual ring elements and subsequently subjecting the individual ring elements to mechanical shape-forming to obtain respective annular metallic elements or profiling the entire tube and dividing the thus profiled tube into individual ring elements comprising respective individual annular metallic sealing elements.
 2. A method for producing annular metallic sealing elements, comprising forming tubes or tube segments from sheet metal strips or foil strips having predetermined thicknesses, lengths, and widths, placing the tubes or tube segments inside each other so as to obtain a tubular multilayer composite operatively connecting mutually opposed end regions of the tubular multilayer composite to each other, and dividing the tubular multilayer composite into individual ring elements and subsequently subjecting the individual elements to mechanical shape-forming to obtain respective annular metallic sealing elements or profiling the entire tube and dividing the thus profiled tube into respective individual ring elements comprising respective individual annular metallic sealing elements.
 3. The method according to claim 1, wherein the winding is helical.
 4. The method according to claim 1, wherein the sheet metal strips or foil strips comprise first and second strips differing from each other in at least one of thickness, length, and width, said first and second strips being connected to each other to form said multilayer composite.
 5. The method according to claim 2, wherein the sheet metal strips or foil strips comprise first and second strips differing from each other in at least one of thickness, length, and width, a first of the tubes or tube segments being formed from the first strip and a second of the tubes or tube segments being formed from the second strip.
 6. The method according to claim 1 or 16, wherein the winding of the respective strips is in the same or opposite directions and the strips are assembled to obtain a tailored blank composite, or a patchwork composite, or a tailored tube composite.
 7. The method according to claim 1 or 2, wherein the mechanical shape-forming comprises engaging the tube or individual ring element with a contour roller and surfaces of a negative mold which mate with the contour roller.
 8. The method according to claim 1 or 2, wherein the mechanical shape-forming comprises hydroforming, rubber pad forming or use of upsetting presses.
 9. The method according to 1 or 2, wherein the strips are brought into operative connection with each other to form a tailored blank or patchwork.
 10. The method according to claim 2, wherein the tubular multilayer composite comprises a tailored tube.
 11. The method according to claim 1 or 2, wherein the strips are coated in some regions or over the entire surface.
 12. A turbocharger sealed by the sealing element produced by the method according to claim 1 or
 2. 13. A motor vehicle exhaust tract sealed by a flange gasket comprising the sealing element produced by the method according to claim 1 or
 2. 14. A motor vehicle transmission housing sealed by the sealing element produced by the method according to claim 1 or
 2. 15. An internal combustion engine comprising a cylinder-head gasket, the cylinder head gasket comprising the sealing element produced by the method of claim 1 or
 2. 16. The method of claim 2, further comprising forming the tubes or tube segments by helical winding of the strips.
 17. The method of claim 1 or 2, wherein said operatively connecting comprises welding or soldering. 